In general, partially or completely edentolous upper jaws can be treated by drilling holes in the jawbone and the consequent insertion of anchoring elements in these holes by the use of preferably cylindrical fixtures with an outer thread and to supply them with single-tooth or bridge prostheses in the latter case with more than one fixture to be applied in the bone in order to retain a bridge construction.
In certain cases when the patient has been edentolous for a long time and for this reason the jawbone has been partly resorbed, the dimension and the retention force of the jawbone is inadequate for the anchoring of one or several fixtures. The patient may thus not be successfully treated with a desirable prosthetic appliance, or may not be willing to accept the risk which in such a case may be considerable, for loosing the prosthesis or a fractured jawbone.